1. Field of the Invention
The present invention relates to desalination and distillation systems, and particularly to a humidification-dehumidification desalination system that may be used for desalination of seawater, for removal of brine from oilfield deposits during pumping and refining, for separation of mixtures of oil and water, and various other uses where it is desired to purify water or separate mixtures.
2. Description of the Related Art
In many areas of the world, fresh water is scarce, but seawater or salt water is abundant. This has led to the development of various desalination systems to remove salts, primarily sodium chloride, from seawater or salt water, both for drinking water and to produce less corrosive water for industrial use.
Conventional distillation with a single heating stage and a single condensation stage is not energy efficient and is cost prohibitive. As a result, various desalination technologies have been developed. One widely used desalination technology is multi-stage flash (MSF) distillation, in which vapor is produced by the sudden inrush of seawater or bring into an evacuated chamber (flashing), followed by condensation of the vapor to obtain fresh water, a process that is repeated sequentially in multiple stages or chambers. Another widely used desalination technology is reverse osmosis (RO), in which pumps are used to drive the seawater or bring feed through a selectively permeable ion exchange membrane. Several other processes are known, including electrodialysis, thermal vapor compression, liquid-liquid extraction, etc. However, each of these processes is expensive, and they each have technical limitations.
More recently, there has been interest in humidification-dehumidification desalination technology, in which a carrier gas is humidified with the seawater or brine, and then dehumidified to obtain fresh water. Such systems are small-scale distillation systems that may make use of solar energy during the humidification stage. Such systems are usually more economical than other desalination technologies, but are less energy efficient. There is a continuing need for improvements in humidification-dehumidification systems to increase energy efficiency, reduce costs, and increase productivity.
Thus, a humidification-dehumidification desalination system solving the aforementioned problems is desired.